The present disclosure relates to a wave power plant for generating electric power in offshore use and, in particular, to a wave power plant comprising a submersible platform.
A multiplicity of wave power plants is known from the prior art, which wave power plants are distinguished essentially according to their place of use, as to whether they are installed on the high sea (offshore), close to the coast or on the coast. Another distinction relates to the form in which the energy is drawn from the wave motion. For instance, buoys float on the water surface, so that a linear generator, for example, can be powered by a lifting and lowering motion of the buoy body. In another plant concept, the so-called “wave roller”, a blade is placed on the seabed, which blade is tilted back and forth due to the motion of the water molecules. The kinetic energy of the blade is converted in a generator, for instance, into electric power. Finally, the concept of the “wave harrow” presents a machine by which energy from sea waves can be converted. In this case, a coupling body, for instance a blade, a rotor, a roll or such a rotation body is mounted in such a way that an orbital motion of the water molecules, as a consequence of the sea wave motion, is likewise converted into an orbital motion of the coupling body, which orbital motion can then be converted by a crank mechanism directly into a torque which can be used for power generation. The coupling body can be constituted by both a drag-type turbine and by a lift-type turbine, and by a combination of these said variants. By the use of hydraulic components and/or by means of a generator, for instance, the tapped usable torque can then be converted into electric current.
Such a plant is planned for offshore use, since here the energy density of waves is particularly high. In this field of application, rigid anchorage of a plant to the seabed is, however, very complex and expensive, if not even technically unfeasible, due to the likely large water depths. In the prior art there has therefore been proposed a so-called self-referencing housing or frame concept, in which a plurality of coupling bodies having the above construction and the above mounting are disposed in a common housing or structure. The housing or structure has a substantially horizontal longitudinal extent and is disposed beneath the water surface. The submersion depth can be varied by floats in or on the structure. Such a structure is hereinafter referred to as the submersible platform.
If the longitudinal extent of the submersible platform is sufficiently large to mount a plurality of coupling bodies thereon, then the forces acting on the submersible platform act, by virtue of the orbital motion of the water molecules as a consequence of the sea wave motion, in different directions and hereby largely offset one another. A largely still position of the submersible platform relative to the orbital motion of the water molecules is thereby obtained. The crank mechanisms of the coupling bodies can thus be supported on the largely static structure or submersible platform and deliver a torque.
At the same time, the generated torques of all individual coupling bodies have the same alignment, since all coupling bodies have the same direction of rotation. The torques generated by the coupling bodies at the crank drives can be added together, irrespective of their point of application on the submersible platform, if they act on the same rigid body, as is the case in the known wave power plants of this design. Due to the same orientation of all coupling body torques, according to the laws of kinetics a coupling body total torque which would set the overall position of the submersible platform in rotation in the rotational direction of the coupling bodies is thus obtained. It should here be pointed out that, without said torque tapping at the crank drives, the structure is not, of course, set in such rotational motion. For this reason, a dosing facility of the torque tapping which can adapt to the below-described measures for compensating the coupling body torque appears particularly advantageous.
The object of the present disclosure is therefore, by suitable means, to keep the wave power plant stable. One aim is, by this means, to generate a corresponding countertorque which keeps the wave power plant, and thus, in particular, also the submersible platform, in position. Another aim is the creation of a self-adjusting system, the countertorque of which varies in dependence on the applied torque. A further aim is, by a combination of said means, to prevent the inducement of a torque into the wave power plant, so that the plant can be kept in stable position. Only then would it be possible to productively tap the torques generated by the coupling bodies at the crank mechanisms and convert them, for instance, into electric power.